[pg-cvs] Patch for Linux mremap

[John Fremlin]

Hi Stelian,

http://www.opengroup.org/onlinepubs/000095399/functions/mmap.html
        
        Existing implementations of mmap() return the value -1 when
        unsuccessful. Since the casting of this value to type void *
        cannot be guaranteed by the ISO C standard to be distinct from a
        successful value, this volume of IEEE Std 1003.1-2001 defines
        the symbol MAP_FAILED, which a conforming implementation does
        not return as the result of a successful call.

I guess whoever wrote the mmap wrapper didn't read the manpage as it
assumes 0 is the bad value. :-(

Here is a horrible hack for osicat. It should probably be changed to
grovel for MAP_FAILED.


diff --git a/posix/early.lisp b/posix/early.lisp
index fa53d4f..ad02b98 100644
--- a/posix/early.lisp
+++ b/posix/early.lisp
@@ -118,6 +118,10 @@
 (defun make-from-pointer-function-name (type-name)
   (format-symbol t "~A-~A-~A-~A" '#:make type-name '#:from '#:pointer))
 
+(declaim (inline minusone-pointer-p))
+(defun minusone-pointer-p (ptr)
+  (null-pointer-p (inc-pointer ptr 1)))
+
 (define-parse-method errno-wrapper
     (base-type &key object error-predicate (return-filter 'identity)
                (error-generator 'syscall-signal-posix-error))
diff --git a/posix/wrappers.lisp b/posix/wrappers.lisp
index 9d7eb0c..d37082c 100644
--- a/posix/wrappers.lisp
+++ b/posix/wrappers.lisp
@@ -59,7 +59,7 @@
   (length ("off_t" off)))
 
 #-windows
-(defwrapper "mmap" ("void*" (errno-wrapper :pointer))
+(defwrapper "mmap" ("void*" (errno-wrapper :pointer :error-predicate minusone-pointer-p))
   (start :pointer)
   (length ("size_t" size))
   (prot :int)
@@ -68,7 +68,7 @@
   (offset ("off_t" off)))
 
 #+linux
-(defwrapper "mremap" ("void*" (errno-wrapper :pointer))
+(defwrapper "mremap" ("void*" (errno-wrapper :pointer :error-predicate minusone-pointer-p))
   (old-address :pointer)
   (old-size ("size_t" size))
   (new-size ("size_t" size))



[The bytemap project has had a correct(?) way of handling this for
nearly a year (http://common-lisp.net/project/bytemap/) if anybody is
interested in a tested cross-Lisp mmap.]